Automatic stroke-changing apparatus



Jan. 31, 1956 w. B.- CROFTON 2,732,723

AUTOMATIC STROKE-CHANGING APPARATUS FOR WINDMILLS Filed 001;. 27. 1952 F1612 NIH-n50 B aeorrau INVENTOR.

A 'TORNEl/ United States Patent 2 7 2 72 nu roiuar c STROKE-CHANGING srranrgrps FOR WrNpMILLs Wilfred l3, Crofton, Johannesburg, Transvaal,

Application October 27, 195;, Serial No. 8 l im 171. 0).

This invention relates to Windmill driven pumps and provides a devic'e for halving the'stiok'e' and load'on the windmill when the wind'l o'ses velocity, whereby the wheel may bekept turning whne umping Waterat a" reduced rate According to the invention a device for the purpose described comprises a pair'of toothed' 'rack's reciprocable in fixed parallel guides and in toothed engagement onopposite sides of a pinion rotationally :rnopnt'ed"o n arneinber reciprocable '-between and parallel'wi'tlf the i acksfa connection between one of theraeks and'th windmill by the windmill.

The invention also consists in a device according to the preceding paragraph wherein thesaid c'ofipliiig 'a'iid uncoupling areeifected auto'm 'ti'cally' thio gh theagen'cy of a member freely hung fro'm'th'e pit '-co hne"cted"rack so as to rise and fall through the full'st'rbk'g' whic member, each down stroke, strikes a' fixed abutment the rack guide system and is swung through an arc whi'ch depends upon the speed of the "st'rokefthe"arrangement being such that when the speedand'the gra er swing of said member diminishes "to a certairi' 'deg'reethe'said member comes into operative engagement with "trip mechanism to efiiect the said uncoupling and divide the stroke between the two racks through the pinion.

The principles of operation of a device a ing to the present invention will be understood from 'thdolloivin}; general description leading to 'the"des'criptio1i"ofa preferred construction of theapparatus witli"re'fierence to drawings accompanying this specification."

The device may comprise in general tw'otoothed racks, .onepinionhetween them, and gu'i'de'means'ifi which the racks slide, together with levers, spring s, bolts ana' e'rossheads, as described hereunder.

The guide system in which the racks slide is formed by two channel irons joined top and bottom; spacsdfso that when the pinion 'gear is meshed intd'and betweeh the toothed r'acks the'assembly ca'risl'ide' frie'elyu'p and down the full stroke of the windmill.

The pinion revolves in a cage which slides between the'edges of the channels. This cage-is attached'tofthe pump rod. The windmill pitin'anorthe equivalent" is attached to one of the racks in a connectionwhicli slid'e's above the pinion cage.

The second rack'is free to move up and down when the pinion cageand the first rack are locked together, and the whole assembly can rise and fall 'tli'frilfslfbke of the windmill. i

-When the said parts are unlocked however, the pitman connection draws itsrack up, rolling" 'the pinion witli'its cage and pump rod up the o'p'pdslite r'ackj thfis h'alvilij'g r 2,732,723 1C6 Batented Jan- 1 3 the stroke of the pump rod and halving the quantity of water pumped'per'stroke;"whereby half the velocity of wind keeps thewheelturning. j

The method of locking and unlocking the parts aforesaid automatically maybe as followsz' The pitman connected rack has a rod fixed tell: which projectsacross the outside of thechannel enclosing the free 'racki a square "ro'd hangs on this bar, a projection on this 'bar strikes a profection' or cam fixedtothe outsideof the channel casing and as the bar rises and falls it swings in a'ii'arc"which is iegulated'by the strength of theblow, or in other words, by the speed of the windmill. The lock which couples the pinion cage and the firstnientioned rack is siihilar to the ordinary door spring lock, such as the Yale, the latch pin sliding in the lower pinion cage" and the latch cavity being provided in' 'the pitmanrack connection. A T-shaped lever is pivoted horizontally on the pinion cage at Ilfe'junction of the 'cross"bar of the .T. The long arm 'of this lever projects over the inside edge of the channel. Theup'pet arm operates the latch pin and the lower a'rm operates a similar sliding pin' at the bottom of thelower cros'shead.

Qth ,pins may be composed of half inch square steel bar. A tension spring keeps theT lever normally in'the position where the long' arm is sloping downwards? the 1 1 p?! arm is holding the latch pip'in locked position (but not necessarily locked) and the lower armin unlocked position. Two light springs tend to keep both latch pins in unlocked positionso that when theft lever pressure is rcmqyed t e lat h pin is jp back to unlocked posiyon 1} stop lever or arm is pivoted at a point at the lower a d of t e h nnel uid sys m n c a way that when it is moved inwards the long arm of the 3' lever meets it on the downstroke which causes the long anti of "the lever to move upwards relative to the pinion cage, thufs pressing the lower pin inwards and removing the inward P e s re Q e l c n tc pin; t q p thn cornesto rest on a fixed seat attached 'tpthechannel case. This action removes the weight of the pump rod firom the top latch pin and allows it to fly back and tin- 1 ook itself without jar.

' e mome h P n Qn case li ts, he o r p v\it hiQeh rnigll t he styled arspacingpim flies back and leaves space between" the bottom of the cage and ,the illicit seat?" Thus, when pumping normally on full s troke,",the weight of the pump rod hangs permanently 013 the assemhlyfwithout striking any part of the case at the' bottom ,of the snake. Only when running on half stroke of actually locking or unloc k ing at the bottom of the stroke acts the pinion'cageactually rest on the seat or'bas'e.

when h ngin -1 t q e t9 h strok e l ck- .ing latchpin'itself, b eingshaped like a ramp similarto an ordinary door lock, pushes the .T lever across, thus sliding ,the spacing pin across before it reaches the' rest s'elaft d'rbl sel i i wreat s pinion cage comes to rest on this pin on the "e t seat the weight of the pump rod is removed from Miller latch pin, itlslides'hackinto unlocked position lthe pinion cage is lifted at half stroke, as before described."

Tofitithis ,rnachine to a windmill it is only necessary tto'ifi x av'vood 'ibeam" across'the windmill towerand hang ithe'fstroke"change device on the beam in line with the 5 mprod and pitma'nwith the stroke change at the hot- ..t pfithe"stroke, and connect the windmill pitman to ith e' top crdsshead and the pump r'odto the bottorn crossh'eadwilhdheIwihilinill' atbottorn dead centre and the p p atjth b" a 'rn of thei stroke;

of e ha nel g' lide ystcm m y e used as a 's'tifnp'to' i'etain oilari'd tnerack nr reeks risin and falling will keep the entire mechanism lubricated. Obviously, weights may be used instead of springs subject to their not adding unduly to the weight and cost of the apparatus.

An improved and preferred embodiment of the invention is shown in the accompanying drawings, wherein:

Figure 1 is a side elevation showing the parts coupled for full stroke direct drive of the pump rod from the windmill pitman or the like;

Figure 2 is a sectional elevation showing the rack and pinion arrangement, with the parts uncoupled except through the driving rack and the pinion for half-stroke operation;

Figure 3 is a cross-section on the line IIIIII of Figure 1; and

Figure 4 is a fragmentary lower-end elevation corresponding to the lower parts of Figure 1 but with the locking mechanism tripped at the bottom of a slow-speed stroke to uncouple or prevent recoupling of the pitman or the like and the pinion-mounting member with which the pump rod is connected.

In these drawings the racks 1 and 2 are slidable together or in reverse directions in guides provided by the two parallel opposed channels 3 and 4 which are cross-connected at their top and bottom ends, and the pinion 5, engaging with the racks, is rotatable on its shaft 6 which is mounted in a cage 7 slidable under guidance from the opposed margins 3' and 4' of the channels.

The connection at 8 between the windmill and the rack 1 is in an integral head portion 1 of the rack casting, and the pump rod 9 is connected at 10 to the base of the cage 7, the rod passing downwardly through a central aperture in the floor of the channel assembly.

The mechanism for coupling the rack 1 directly to the pinion cage 7 consists of a U-shaped latch 12 pivotally connected to the cage via the ends of the pinion shaft 6, which latch may fit into a recess 13 formed in the rack head, to couple the parts as shown in Figure 1.

The latch is urged normally into its upright position '(see Figure 2) by an arm 14 (see Figures 1 and 3) against a stop 15 on the pinion cage 7, the tail 14' of the arm being loaded upwardly by the tail 16 of a further arm 16 pivoted at 17 to the side of the cage, the opposite extremity 16" of which arm 16 is biased by a tension spring 18 anchored by a bracket 19 also to the cage. Biased thus the latch 12 will tend to enter and remain in the recess 13, being guided into position by the ramp surface 13' which first engages the top of the latch when the rack 1 runs down the guides past the p1n1on cage.

- Referring to Figure l, with the parts coupled as there shown for full stroke working, a further arm 20 is pivoted at 20' to the side of the channel 3 and is loaded by a system of compression springs 21 and guide rods 21' outwardly into engagement with an abutment plate 22 attached to the same channel, and by shaping the arm 20 and the plate 22 as shown a throat 23 is defined between them when they are in contact.

From a bracket 24 projecting sidewise from the head 1 of the rack 1, a member 25 is freely suspended on a transversely arranged pivot pin 26, the lower and free end 25' of the member 25 being pointed and capable, when the rack 1 is lowered slowly, of being driven into the throat 23 aforesaid as the bottom end of the full pumping stroke is being approached. As a result of this action, when it is permitted to occur, the arm 20 is forced over against its spring system 21, 21 into the position shown in Figure 4, thereby presenting an abutment 20' in the downward path of the end 16" of the spring loaded arm 16. On the parts meeting, the arm 16 is rocked into the position shown, thereby relieving the erecting force through the arm 14 on the latch, which under the action of a weighted lever 27 is withdrawn from the recess 13 in the rack head, the parts being thus uncoupled.

So long as the speed of operation is low enough for the member 25 to function as explained, at the lower end of the stroke, the latch is prevented from coupling the pump rod to the pitman drive rack 1.

Adverting now to the operation of the swinging member 25 at normal or high speeds when full stroke functioning is required, a fixed abutment 28 on the channel 3 is so positioned as to lie in the path of a projection 29 fixed on the member 25, as the latter is lowered with the rack head 1, and thereby as the lower end of each stroke is approached to receive a knock swinging the member 25 outwardly (in relation to the plane of the drawings) through an are which increases with the speed of the windmill and is ordinarily so great that the pointed end 25' of the member 25 is prevented from entering the throat 23 aforesaid. In thus working the latch mechanism already described is not tripped at the normal or higher speeds but only when the speed drops to a value so low that half-stroke working is required to keep the pump in operation, in which condition the mechanism will continue to be tripped at the end of each downward stroke to prevent relocking of the latch and coupling of the pitman or the like in effect directly to the pump rod.

Additionally the arm 20 is arranged in being moved into the position shown in Figure 4 to push a slide 30 across the floor 11 of the channel guide system into the position shown in Figure 2, i. e. below the lower end of the free rack 2 whereby to take the weight of the pump rod (through the pinion cage) at the bottom of each stroke, thus relieving the load on the latch for free movement of the latter into unlocked position in conditions when the member 25 is operative.

What I claim is:

1. An automatic stroke changing device for coupling a reciprocable driven member to a reciprocating driving member, comprising fixed parallel guides, a pair of toothed racks reciprocable in said guides and disposed with their toothed sides facing and spaced from one another, a cage reciprocable parallel to said racks, a pinion rotatably mounted in said cage and meshing with both of said racks, driving connection between said driving member and one of said racks, herein designated the driven rack, the other of said racks, being freely reciprocable within fixed limits, a stop for limiting the movement of said other rack, driving connections between said cage and said driven member, means for releasably coupling said cage to said driven rack so that both racks and said cage reciprocate together and means responssive to the speed of reciprocation of the driving member for uncoupling said cage from the driven rack when said speed drops below a predetermined value so that the pinion is driven by the driven rack, the other rack being held stationary at one limit of its movement by said stop, and the cage is thereby driven by said pinion at half the speed and through half the stroke of said driven rack.

2. An automatic stroke changing device for coupling a reciprocable driven member to a reciprocating driving member, comprising fixed parallel guides, a pair of toothed racks reciprocable in said guides and disposed with their toothed sides facing and spaced from one another, a cage reciprocable parallel to said racks, a pinion rotatably mounted in said cage and meshing with both of said racks, driving connection between said driving member and one of said racks, herein designated the driven rack, the other of said racks being freely reciprocable within limits, a stop for limiting the movement of said other rack, driving connections between said cage and said driven member, latch means for releasably coupling said cage to said driven rack so that both racks and said cage reciprocate together, said latch means being movable between a latched position and an unlatched position, trip means for moving said latch to an unlatched position to uncouple said cage from said driven rack so that said pinion is driven by said driven rack, the other rack being held stationary by said stop, and the cage is thereby moved by said pinion at half the speed and through half the stroke of the driven rack, said trip means comprising a trip member swingably carried by said driven rack and biased to a rest position in which it is effective to release said latch means, and a fixed deflecting member positioned to engage said trip member as said driven rack reciprocates and thereby swing said trip member from said rest position through an arc the amplitude of which varies with the speed of movement of said driven rack.

3. An automatic stroke changing device for coupling a reciprocable driven member to a reciprocating driving member, comprising fixed parallel guides, a pair of toothed racks reciprocable in said guides and disposed with their toothed sides facing and spaced from one another, a cage reciprocable parallel to said racks, a pinion rotatably mounted in said cage and meshing with both of said racks, driving connection between said driving member and one of said racks, herein designated the driven rack, the other of said racks being freely reciprocable within limits, a stop for limiting the movement of said other rack, driving connections between said cage and said driven member, an abutment on said driven rack, a latch pivotally mounted on said cage and swingable from a released position to a latched position in which it engages said abutment to couple said cage to the driven rack so that both racks and said cage reciprocate together, and trip means for swinging said latch to released position at the end of a stroke to uncouple said cage from said driven rack so that said pinion is driven by said driven rack, the other rack being held stationary by said stop, and the cage is thereby moved by said pinion at half the speed and through half the stroke of the driven rack.

4. A device according to claim 3, in which said trip means comprises a trip member swingably carried by the driven rack and biased to a rest position in which it is effective to release said latch, and a stationary deflecting member positioned to engage said trip member as said driven rack reciprocated and thereby swing said trip member from said rest position through an arc the amplitude of which increases with increase of speed of said driven rack.

5. An automatic stroke changing device for coupling a reciprocable driven member to a reciprocating driving member, comprising fixed parallel guides, a pair of toothed racks reciprocable in said guides and disposed with their toothed sides facing and spaced from one another, a cage reciprocable parallel to said racks, a pinion rotatably mounted in said cage and meshing with both of said racks, driving connection between said driving member and one of said racks, herein designated the driven rack, the other of said racks being freely reciprocable within limits, a stop for limiting the movement of said other rack, driving connections between said cage and said driven member, an abutment on said driven rack, a latch pivotally mounted on said cage and swingable from a released position to a latched position in which it engages said abutment to couple said cage to the driven rack so that both racks and said cage reciprocate together, means for biasing said latch to latched position, and trip means for swinging said latch to released position at the end of a stroke to uncouple said cage from said driven rack so that said pinion is driven by said driven rack, the other rack being held stationary by said stop, and the cage is thereby moved by said pinion at half the speed and through half the stroke of the driven rack, said trip means comprising an arm pivoted on said guides, a stationary cam surface, means for swinging said arm toward said cam surface to an inactive position, a swingable trip member pivotally carried by said driven rack and biased to a rest position in which it comes between said arm and said cam surface as the driven rack approaches the end of a stroke and thereby swings said arm to an active position, operative connections between said arm and said latch to release said latch when said arm is in active position, and a stationary deflecting member positioned to engage said trip member as said driven rack reciprocates and thereby swing said trip member from said rest positionthrough an arc the amplitude of which increases with increase of speed of said driven rack, said arm and cam surface being so positioned that when said trip member is swung a predetermined amount it does not come between them.

6. An automatic stroke changing device for coupling a vertically reciprocable pump rod to a vertically reciproeating driving member, a pair of vertically reciprocable parallel racks disposed with their toothed sides facing and spaced from one another, means for guiding said racks, a cage reciprocable parallel to said racks, a pinion rotatably mounted in said cage and meshing with both of said racks, means for connecting one of said racks, herein designated the driven rack, with the driving member, the other of said racks being freely reciprocable within limits, a stop for limiting the movement of said other rack, means for connecting said cage tothe pump rod, means for releasably coupling said cage to said driven rack so that both racks and said cage reciprocate together, means responsive to the speed of reciprocation of the driven rack for uncoupling said cage from the driven rack when said speed drops below a predetermined value so that the pinion is driven by said driven rack, the other rack being held stationary by said stop and the cage is thereby driven by said pinion, and means for temporarily supporting said pump rod at the lower end of its stroke to relieve said coupling means of the load of said rod and thereby facilitate its release.

7. An automatic stroke changing device for coupling a vertically reciprocable pump rod to a vertically reciprocating driving member, a pair of vertically reciprocable parallel racks disposed With their toothed sides facing and spaced from one another, means for guiding said racks, a cage reciprocable parallel to said racks, a pinion rotatably mounted in said cage and meshing with both of said racks, means for connecting one of said racks, herein designated the driven rack, with the driving member, the other of said rack-s being freely reciprocable within limits, a stop for limiting the movement of said other rack, means for connecting said cage to the pump rod, latch means for releasably coupling said cage to said driven rack so that both racks and the cage reciprocate together, said latch means being movable between a latched and an unlatched position, trip means for moving said latch means to unlatched position at the end of a downward stroke of said driven rack to uncouple said cage from said driven rack so that said pinion is driven by said driven rack, the other rack being held stationary by said trip, and the cage is thereby moved by said pinion, said trip means comprising an inertia operated trip member carried by said driven rack.

8. A stroke changing device for coupling a vertically reciprocable pump rod to a vertically reciprocable driving member, a pair of vertically reciprocable parallel racks disposed with their toothed sides facing and spaced from one another, a cage reciprocable parallel to said racks, a pinion rotatably mounted in said cage and meshing with both of said racks, means for connecting one of said racks, herein designated the driven rack, with the driving member, the other of said racks being freely reciprocable within limits, a stop for limiting the movement of said other rack, means for connecting said cage to the pump rod, means for releasably coupling said cage to said driven rack so that both racks and the cage reciprocate together and means for releasing said coupling means so that said driven rack drives said pinion, the other rack being held stationary by said stop, and the cage is thereby moved by the pinion at half the speed and through half the stroke of said driven rack.

No references cited. 

